Coproduction of Methanol and Dimethyl Ether from Biomass-Derived Syngas on a Cu−ZnO−Al₂O₃/γ-Al₂O₃ Hybrid Catalyst

Abstract

The coproduction of methanol (MeOH) and dimethyl ether (DME) from biomass-derived synthesis gas on the coprecipitated Cu-ZnO-Al 2 O 3 /γ-Al 2 O 3 hybrid catalysts has been investigated to overcome the equilibrium conversion of CO on the MeOH only synthetic reaction at the H 2 -decificient condition. Two different types of γ-Al 2 O 3 were employed as the solid-acid component of hybrid catalyst: one prepared by a precipitation method and the other prepared by a sol-gel method. Several hybrid catalysts were prepared by the coprecipitation method in the slurry of γ-Al 2 O 3 with the variation in the weight ratio of MeOH synthesis catalyst (Cu-ZnO-Al 2 O 3 ) to solid-acid catalyst (γ-Al 2 O 3 ) as well as by changing aging time during synthesis. The catalytic activity results revealed that the best yield of MeOH and DME with concomitant decrease in the CO 2 formation was obtained on the hybrid catalyst containing γ-Al 2 O 3 prepared by the sol-gel method with an aging time of 6 h. The hybrid catalysts were characterized by using the BET surface area measurements, NH 3 temperature programmed desorption (NH 3 -TPD), scanning electron microscopy (SEM), temperature programmed reduction (TPR), and X-ray diffraction (XRD) methods. The observed catalytic properties were related to the surface area of Cu metal, dispersion of Cu-ZnO-Al 2 O 3 particles, and reducibility and acidity of hybrid catalysts. The enhanced catalytic activity with low selectivity to CO 2 is attributed to the facile reducibility of welldispersed copper oxides at low temperatures and also to the benign acid strength of the hybrid catalysts.

Effect of Active Component Contents to Catalytic Performance on Fe-Cu-K/ZSM5 Fischer-Tropsch Catalyst

“…It can be seen that the pore size distribution shows a sharp peak in the micropore region and a broad peak enveloping meso-and macropore region. The micropore region peak can be attributed to the pores of ZSM5 and the meso-and macropores observed are related to active component pores of interparticulate void space [12,13]. The micropore distribution can be seen clearly in the in-set given in Fig.…”

Production of Biomass-Derived Chemicals and Energy: Chemocatalytic Conversions of Glycerol

“…The catalyst Cu-ZnO-Al 2 O 3 /c-Al 2 O 3 was prepared by co-precipitation on c-Al 2 O 3 (Alfa Aesar) powder according to [41]. The desired amounts of copper acetate (4.57 g, Merck), zinc nitrate (5.82 g, Merck) and aluminium nitrate (2.97 g, Alfa Aesar) were dissolved in 600 mL of distilled water.…”

“…After the precipitation the slurry was further stirred at 70°C for 2 h. Then the catalyst was filtered, washed with hot distilled water and dried at room temperature over night. This material was heated in a stream of hydrogen within 30 min to 300°C, the temperature was held for 2 h [41].…”

Activity and deactivation studies for direct dimethyl ether synthesis using CuO–ZnO–Al2O3 with NH4ZSM-5, HZSM-5 or γ-Al2O3

“…For the former the methanol synthesis and methanol dehydration catalyst components exist together as a single entity [11]. Such catalysts are generally prepared by coprecipitation or mixing of the freshly precipitated precursors [12][13][14][15]. While in the case of the admixed catalyst each function is prepared (synthesized) separately and then the powders of both functions are mechanically blended [16][17][18][19][20][21][22].…”